In the conventional art, comparators are utilized to monitor an input voltage. Referring to FIG. 1A, an exemplary comparator in accordance with the convention art is shown. The comparator compares the input voltage (VI) with a reference level (VR). The reference voltage constitutes the comparator threshold. The comparator outputs an output voltage (VO) as a function of the relative difference between the input voltage (VI) and the reference voltage level (VR). The transfer characteristics of the exemplary comparator is shown in FIG. 1B. If the input voltage (VI) is greater than the reference voltage (VR) the comparator provides an output signal having a first state (L+) (e.g., high state). Alternatively, if the input voltage (VI) is less than the reference voltage (VR) the comparator provides an output signal having a second state (L−) (e.g., low state).
However, prior art comparators are disadvantageous because an input voltage event (e.g., overvoltage or undervoltage event) is not correlated with the time the event occurred. For example, although a comparator determines that the monitored input voltage exceeded a maximum voltage limit during a test sequence, the automatic test equipment performing the test, due to its periodic nature, is unable to determine from the comparator at what time during the test the overvoltage event(s) occurred.